JPH08292336A - Production of optical semiconductor integrated circuit - Google Patents

Abstract

PURPOSE: To form plural crystal growth layers having a large difference in wavelength compsn. by one time of crystal growth stage. CONSTITUTION: Plural pairs of masks 22 for selective crystal growth to be paired are formed on an n-InP substrate 11 by varying mask widths (only one pair of the masks are shown in Fig.). An n-InGaAsP layer 12, n-InP spacer layer 13, lower SCH layer (light confinement layer) 14, MQW layer 15, upper SCH layer 16 and InP clad layer 17 are successively selectively grown on the n-InP substrate 11 by an org. metal vapor growth method regulating a growth pressure to >=500Torr [Fig. (a)]. The masks 22 are removed and an InP embedment layer 18 is formed [Fig. (b)].

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical semiconductor integrated circuit, and more particularly to a method for manufacturing an optical semiconductor integrated circuit including a step of forming a plurality of semiconductor layers having different wavelength compositions by one selective growth. It is a thing.

[0002]

2. Description of the Related Art An optical semiconductor integrated circuit in which a passive optical waveguide and an active optical element are integrated on the same substrate has attracted attention as a small and multifunctional device. As one of such optical semiconductor integrated circuits, WDM (Wave Division Multiplexing:
(Wavelength multiplex) coupler, 1.3 μm band photodiode (PD), 1.55 μm band laser (LD), LD
A WDM transmitter in which a monitor PD and a PD are integrated on the same substrate is described by R. Wats et al. In “Integrated Photoni
cs Research '94 Post Deadline Paper PD1-
1 ”.

In this WDM transmitter, the signal (received signal) from the host side to the transmitter side is 1.3 μm.
The signal from the transmitter side to the host side (transmitting signal) is in the 1.55 μm band, and transmission and reception are performed using light in the 1.3 μm band and 1.55 μm band with one optical fiber. In this WDM transmitter, a WDM coupler for branching / combining different wavelengths is composed of a passive waveguide, and the wavelength composition of its core layer is 1.1.
5 μm.

On the other hand, the wavelength composition of the 1.55 μm band LD core layer and the LD monitor PD core layer, which are active devices, is 1.55 μm, and the 1.3 μm band PD core layer wavelength composition is 1.3 μm. is there. Therefore, in such a WDM transmitter, crystals of at least three different wavelength compositions are required, so that unnecessary portions are etched after growing crystals of one wavelength composition, and crystals of other wavelength compositions are grown again. That is, it is manufactured by repeating the crystal growth process and the etching process. Therefore, there is a problem that the process is complicated and a high yield cannot be obtained.

As a method for solving this problem, an organometallic film is used which simultaneously forms crystals having different wavelength compositions and different growth layer thicknesses by changing the mask width of a pair of stripe-shaped masks used for selective crystal growth. The selective vapor phase growth method used by Kato et al., Electronics Letters Vol.
28 p.153. When a multi quantum well (MQW) layer is manufactured based on this principle, the wavelength composition of the MQW layer changes due to the difference in the well layer wavelength composition and the well layer thickness of the MQW due to the difference in the mask width. As shown in this report example, conventionally, the growth pressure was 1
The selective crystal growth was performed by reducing the pressure to / 10 atm.

[0006]

As described above, in the conventional selective crystal growth method, the growth pressure was reduced to 1/10 atmospheric pressure for growth. FIG. 6 shows an experimental result of the relationship between the growth pressure and Δλ (wavelength composition difference of MQW layer between mask width Wm = 2 μm and Wm = 30 μm).
At rr, Δλ is only about 200 nm.

FIG. 7 shows an experimental result of the relationship between the wavelength composition and the waveguide loss of the passive waveguide measured with the 1.3 μm band signal light. As is clear from this, at least the wavelength composition must be 1.25 μm or less in order to prevent the waveguide loss of the passive waveguide from becoming excessive. That is, a WDM coupler composed of a passive waveguide and 1.3 μm
In order to realize the core layers of the band PD and the 1.55 μm band LD in the same crystal growth step, a wavelength composition difference of 300 nm or more is necessary. Therefore, it has been impossible to realize an optical semiconductor integrated circuit in which these elements are integrated by the conventional selective crystal growth method in which the growth pressure is about 1/10 atmospheric pressure.

The present invention has been made in view of this point, and an object thereof is to form at least 300 nm when forming a plurality of MQW core layers having different composition wavelengths by a selective crystal growth method with different mask widths. The above wavelength composition difference is at least 150 μm when the bulk core layer is formed.
It is an object of the present invention to provide a crystal growth method capable of obtaining the above wavelength composition difference.

[0009]

In order to solve the above problems, according to the present invention, (1) a step of depositing a dielectric film on a semiconductor substrate, and (2) selecting the dielectric film. And removing a plurality of masks each consisting of a pair of stripe-shaped dielectric films having a predetermined width and forming a pair of stripe-shaped dielectric films having a predetermined width, and (3) a growth pressure of 500 T in the space of the mask.
a step of selectively growing the semiconductor core layer by a vapor deposition method of orr or higher; (4) expanding the void portion of the mask or removing the mask and depositing a dielectric film again to form a striped dielectric film. And a step of forming a buried layer surrounding the semiconductor core layer after processing or removing the mask, a method for manufacturing an optical semiconductor integrated circuit is provided.

Further, preferably, the semiconductor core layer is formed by a metal organic chemical vapor deposition method. The semiconductor core layer is made of InGaAs, InGaAsP, InGaAl.
A bulk layer formed using As or InGaAlAsP, or a multiple quantum well layer having a layer formed of one of these materials as a well layer is formed.

[0011]

In the present invention, the growth pressure during selective crystal growth is set to 5
It is set to 00 Torr or more. Therefore, when the MQW layer is grown, a semiconductor crystal layer having a wavelength composition difference of at least 300 nm or more can be obtained in one crystal growth step. Therefore,
M of a passive waveguide having a wavelength composition of at least 1.25 μm or less
The QW core layer, the MQW core layer of the 1.3 μm band active optical element, and the MQW core layer of the 1.55 μm band active optical element can be formed by one crystal growth step. Moreover,
A plurality of optical elements having different wavelength compositions can be continuously formed in the light propagation direction.

When bulk growth is performed in the present invention, a wavelength composition difference of at least 150 nm or more can be obtained. Therefore, the bulk core layer of the passive waveguide having a composition of at least 1.15 μm and the bulk core layer having a composition of 1.3 μm can be formed by one crystal growth step. Alternatively, the bulk core layer of the passive waveguide having a composition of at least 1.4 μm and the bulk core layer having a composition of 1.55 μm can be formed by one crystal growth step. Moreover, a plurality of optical elements having different wavelength compositions are continuously formed in the light propagation direction.

[0013]

Next, embodiments of the present invention will be described in detail with reference to the drawings. [First Embodiment] FIG. 1 is a perspective view of an optical semiconductor integrated circuit formed according to the first embodiment of the present invention. This embodiment relates to an optical semiconductor integrated circuit for a video on demand (VOD) optical terminal. As shown in FIG. 1, directional coupler type WDM coupler 1, Y branch 2, 1.3 μm
LD3 for band transmission, PD4 for 1.3 μm band reception and 1.
The PD 5 for receiving in the 55 μm band is integrated. The optical semiconductor integrated circuit according to the present embodiment has a 1.3 μm band and a 1.55 μm band.
It is configured as a VOD optical terminal that receives two types of signals in the m band as wavelength division multiplexed signals and sends transmission signals in the 1.3 μm band.

2 (a), (b), (c) and (d),
The lines AA ', BB', CC 'in FIG.
It is sectional drawing in the DD 'line cross section. As shown in FIG. 2, each element is formed on the n-InP substrate 11, n
-InGaAsP layer 12, n-InP spacer layer 13,
Lower SCH (Separate Confinement Hetero-structure)
) Layer 14, MQW layer 15, upper SCH layer 16, InP
It is constituted by the cladding layer 17, and is embedded by the InP burying layer 18.

Next, a method of manufacturing the optical semiconductor integrated circuit shown in FIGS. 1 and 2 will be described with reference to FIGS. First, as shown in FIG. 3 (a), a SiO ₂ film 21 is formed on the n-InP substrate 11 by heat C to a film thickness of about 1000 Å.
It is deposited by the VD method. The n-InP substrate 11 has a structure shown in FIG.
As shown in (b), the grating 20 is provided in advance only on the LD portion. The grating 20 is manufactured by a normal interference exposure method or EB (ElectronBeam).
An exposure method is used.

S is formed by using a normal photolithography technique.
The iO ₂ film 21 is selectively removed, and a pair of stripe-shaped masks as shown in FIG. 3B is formed as a mask 22 for selective crystal growth. The width Wm of the mask 22 is W in the WDM coupler 1 and the Y branch 2 which are passive waveguides.
m = 2 μm, LD3 for 1.3 μm band transmission and 1.3 μm
In the m-band receiving PD 4, Wm = 10 μm, and in the 1.55 μm-band transmitting PD 5, Wm = 30 μm. The mask gap Wg is 2 μm in all the regions.

After that, as shown in FIG. 4A, n-InGaA is formed by a metal organic chemical vapor deposition (MO-CVD) method.
The sP layer 12, the n-InP spacer layer 13, the lower SCH layer 14, the MQW layer 15 composed of the InGaAsP well layer / InGaAsP barrier layer, the upper SCH layer 16, and the InP clad layer 17 are sequentially and selectively grown. Organic metals include TMI (trimethyl indium), TMG
(Trimethylgallium) is used, and As is used as the group V gas.
H ₃ and PH ₃ are used, and Si ₂ H ₆ is used as a doping gas. The growth pressure is 500 Torr.

A description will be given centering on the portion selectively grown in the region where the mask width Wm is Wm = 10 μm. The wavelength composition and the growth layer thickness of each growth layer are n-InGaAsP layer 12
Has a wavelength composition of 1.15 μm, a growth layer film of about 1000 Å,
The n-InP spacer layer 13 has a growth layer thickness of about 400Å, the lower SCH layer 14 has a wavelength composition of 1.15 μm, and a growth layer thickness of 10
In the MQW layer 15, the InGaAsP well layer has a wavelength composition of 1.4 μm, the growth layer thickness is about 45 Å, and the MQW layer 15 has 7 periods.
The nGaAsP barrier layer has a wavelength composition of 1.15 μm, the growth layer thickness is about 100 Å, and the upper SCH layer 16 has a wavelength composition of 1.15.
μm, growth layer thickness of about 1000Å, InP clad layer 17
Is a growth layer thickness of about 2000Å.

Next, the selective crystal growth mask 22 is removed with buffered hydrofluoric acid to grow the InP burying layer 18 on the entire surface (see FIG. 4B). The thickness of the grown layer is about 2 μm. After that, by a normal selective diffusion process, 1.3μ
LD3 for m band transmission, PD4 for 1.3 μm band reception, 1.5
Zn is diffused immediately above the PD 5 for receiving in the 5 μm band, and metal for electrodes is vapor-deposited. Then, the back surface is polished and metal for electrodes is deposited to complete the fabrication of the device.

The manufacturing method of the optical semiconductor integrated circuit according to the first embodiment of the present invention is as described above.
The principle of obtaining the W core layer in the same selective crystal growth step will be described below.

In the method for manufacturing an optical semiconductor integrated circuit according to the present invention, selective crystal growth is performed at a growth pressure of 500 Torr. FIG. 5 is a graph showing the experimental results of the relationship between the wavelength composition of the MQW layer composed of the InGaAsP well layer / InGaAsP barrier layer grown at 500 Torr and the mask width of the SiO ₂ mask used for selective crystal growth. . The wavelength composition was obtained from the peak of the emission spectrum by the photoluminescence method.

In general, when a material containing In and Ga, such as InGaAs and InGaAsP, is selectively grown by the metal organic chemical vapor deposition method, the wider the mask width, the higher the In incorporation rate into the solid phase. It is known that as the wavelength composition becomes longer, the growth rate becomes faster and the growth layer thickness becomes relatively thicker. Therefore, as shown in FIG. 5, when the MQW layer is selectively grown, the wavelength composition becomes longer as the mask width used for the selective crystal growth becomes wider.

FIG. 6 shows the growth pressure and wavelength composition difference Δλ (mask width Wm = 2 μm and Wm = 30 μm) during selective crystal growth.
As shown in the figure, if the growth pressure is 500 Torr or more, Δλ
≧ 300 nm. Therefore, in the past, selective crystal growth of InP-based materials by the metal organic chemical vapor deposition method was generally performed under a reduced pressure of about 1/10 atm, whereas in the present invention, it is as high as 500 Torr. Growth takes place under pressure.

Generally, when the growth pressure is high, II in the gas phase
The concentration gradient of the group I material becomes large. At this time, In and G
The difference in the diffusion constant of a becomes large, and the rate of incorporation of In into the solid phase becomes larger. As a result, a larger wavelength composition difference can be obtained. That is, such a large wavelength composition difference can be obtained by increasing the growth pressure.

FIG. 7 shows an experimental result of the relationship between the waveguide loss and the wavelength composition of the passive waveguide (using MQW as the core layer) for 1.3 μm band signal light.
It can be seen that the loss of the passive waveguide becomes extremely large unless the thickness is 5 μm or less. Therefore, the wavelength composition of the low-loss passive waveguide must be 1.25 μm or less.

From this result, it is confirmed that the passive waveguide and 1.3 μm
In order to integrate the band emitting / receiving element and the 1.55 μm band receiving element, it is necessary that Δλ ≧ 300 nm. In this example, since Δλ = 300 μm, 1.3 μ
a core layer of a passive waveguide having a wavelength composition of 1.25 μm, which is a wavelength composition transparent to light in the m band and 1.55 μm band, and a core layer of LD and PD having a wavelength composition of 1.3 μm, The PD core layer having a wavelength composition of 1.55 μm can be realized at the same time by one crystal growth step. If the growth pressure is 250 Torr, Δλ =
It is about 250 nm.

Therefore, although the core layer of the passive waveguide having the wavelength composition of 1.25 μm and the core layer of the 1.3 μm band active optical element can be realized by the same crystal growth process, the core layer of the 1.55 μm band active optical element can be obtained. Cannot be made at the same time. in this case,
It is necessary to repeat the crystal growth step of the core layer at least twice and remove the extra crystal growth layer by an etching step or the like. As described above, in the present embodiment, since it is not necessary to repeat the conventional crystal growth process and etching process, it is possible to secure high yield and reproducibility.

Further, since each core layer is continuously formed, the coupling loss hardly occurs, and each core layer is formed by the selective crystal growth method, and the etching process is not used. Therefore, the waveguide is not formed. Side walls are smooth and scattering loss does not occur. Therefore, an optical semiconductor integrated circuit with a small internal loss can be obtained.

In this embodiment, SiO ₂ is used as the mask material for selective crystal growth, but the mask material is not limited to this, and may be SiN, for example, or the thermal CVD method as the deposition method. Plasma CVD
May be law. In addition, as an organic metal material, TMG,
Although TMI is used, it is not limited to this, and for example, TE
G (triethylgallium) or the like may be used. Also, V
Although AsH ₃ and PH ₃ are used as the group gas, the present invention is not limited to this, and, for example, TBA (tertial butyl arsine) and TBP (tertiary butyl phosphine) which are organic metal materials can be used.

Further, in the above embodiment, the InGaAsP layer was used as the well layer and the barrier layer, but instead of this,
InGaAs, InGaAlAs or InGaAlA
sP can be used as a well layer or a barrier layer. At that time, the well layer and the barrier layer do not necessarily need to be materials containing the same element. Further, in the above-mentioned examples, the p-type conversion was performed by using the selective diffusion step, but the present invention is not limited to this, and for example, DMZn (dimethyl zinc) which is a dopant is used during the crystal growth step. Doping can also be performed.

[Second Embodiment] FIG. 8 is a diagram showing an optical semiconductor integrated circuit formed according to the second embodiment of the present invention. FIG. 8A is a 2 × 2 matrix optical switch. FIG. 8B is a matrix configuration diagram of the branch /
A perspective view of an integrated portion of a gate portion and a branching / multiplexing waveguide portion of an LD amplifier gate type optical switch is shown. FIG.
As shown in (a), the light input from the left side of the drawing into the combining / branching waveguide section 102 is branched and then transmitted / blocked by the gate section 101. Gate part 1
The light transmitted through 01 is combined in the combining / branching waveguide portion 102 and then emitted to the right side of the drawing.

As shown in FIG. 8B, the gate portion 1
No. 01, the composition I of 1.3 μm was formed on the n-InP substrate 111.
nGaAsP active core layer 113, p-InP clad layer 114, p-InGaAs cap layer 115, A
The u / Ti metal layer 116 is laminated, and in the multiplexing / branching waveguide portion 102, 1.15 μm is formed on the n-InP substrate 111.
Composition InGaAsP passive core layer 112, p-InP
The clad layer 114 has a laminated structure.

As described above, the gate region having an optical amplifier composed of the active core layer 113 having a wavelength composition of 1.3 μm as a gate, and the passive core layer 11 having a wavelength composition of 1.15 μm.
The branching / multiplexing waveguide region consisting of 2 is integrated on the same substrate, and the active core layer and the passive core layer are formed continuously in the waveguide direction.

Next, a method of manufacturing the branching / LD amplifier gate type optical switch according to this embodiment will be described with reference to FIG. 9A to 9D are perspective views in order of steps for explaining this embodiment [FIG. 9 (b) is a plan view]. First,
As shown in FIG. 9A, a SiO ₂ film 121 is deposited on the n-InP substrate 111 by a thermal CVD method to a film thickness of about 1000 Å. Thereafter, as shown in the plan view of FIG. 9B, the SiO ₂ film 121 is selectively removed by using a normal photolithography technique to form a stripe-shaped mask 122 for selective crystal growth.

The mask width of the selective crystal growth mask 122 is 30 μm for forming the active core layer in the gate portion 101, and 10 μm for forming the passive core layer in the branching / multiplexing waveguide portion 102. These two types of masks are continuously formed. The length of the gate portion 101 is about 500 μm, and the gap 123 of the mask for selective crystal growth is 0.5 μm.
It is a degree.

After that, as shown in FIG. 9C, undoped I is deposited by using a metal organic chemical vapor deposition (MO-CVD) method.
An nGaAsP core layer is grown to a thickness of 2000Å. At this time, 1.3 is present in the gap 123 of the gate portion 101.
The InGaAsP active core layer 113 having a composition of μm is 1.15 μm in the void 123 of the multiplexing / branching waveguide portion 102.
A composition InGaAsP passive core layer 112 is formed. Thereafter, the width of the void 123 of the selective crystal growth mask 122 is widened by using a normal photolithography technique.

The width of the widened void is about 7 μm.
After that, the p-InP cladding layer 114 and the p-InGa are formed.
The As cap layer 115 is sequentially grown by using the metal organic chemical vapor deposition method. The thickness of the p-InP clad layer 114 is 1
The thickness of the p-InGaAs cap layer 115 is about 2000 μm. Thereafter, as shown in FIG. 9D, the p-InGaAs cap layer 115 on the branching / multiplexing waveguide portion 102 is removed by using a normal photolithography method.

Finally, p-InGaA of the gate part 101 is formed.
An Au / Ti metal layer 116 is formed on the s cap layer 115 using an electron beam evaporation method (EB method). The selective crystal growth mask 122 may or may not be removed thereafter. Through the above steps, the optical switch shown in FIG. 8A is completed.

As described above, in the present embodiment, the present invention is applied to the method for manufacturing the branch / LD amplifier gate type optical switch, and the method for manufacturing the branch / LD amplifier gate type optical switch according to the present invention is used. The principle by which a bulk core layer having a wavelength composition difference of 150 nm or more can be obtained in the same selective crystal growth step will be described below.

In the method of manufacturing an optical semiconductor integrated circuit according to this embodiment, the growth pressure is 500 Torr as in the first embodiment.
The selective crystal growth is carried out in. 50 in FIG.
6 is a graph showing the experimental results of the relationship between the wavelength composition of the InGaAsP bulk grown at 0 Torr and the mask width of the SiO ₂ mask used for selective crystal growth. First
InGaAs, In,
When a material containing In and Ga such as GaAsP is selectively grown by a metal organic chemical vapor deposition method, the wider the mask width, the higher the In incorporation rate into the solid phase and the longer the wavelength composition.

Therefore, when the bulk layer is selectively grown as shown in FIG. 10, the wavelength composition becomes longer as the mask width used for the selective crystal growth becomes wider. Selective crystal growth of InP-based materials by metalorganic vapor phase epitaxy is 1 /
In general, it is performed under a reduced pressure of about 10 atm. In this embodiment, as in the first embodiment, 500 T is used.
Since the growth is performed under a pressure as high as orr, the difference between the diffusion constants of In and Ga becomes larger than in the conventional case, and the rate of incorporation of In into the solid phase becomes larger. As a result, a larger wavelength composition difference can be obtained.

That is, by increasing the growth pressure, a large wavelength composition difference of 150 nm or more can be obtained even in the bulk crystal. FIG. 11 shows the relationship between the wavelength composition of the waveguide and the waveguide loss (wavelength of measurement light: 1.3 μm) when the bulk layer is used as the core layer. As is clear from the figure, when the wavelength composition is 1.2 μm or less, absorption due to band edge absorption is almost eliminated, and when the wavelength composition is 1.15 μm, almost no waveguide loss occurs.

The bulk layer is used as the core layer in the present embodiment, which is different from the first embodiment, for the following reason. This optical switch uses a semiconductor optical amplifier as a gate. In general, when the core layer of an optical amplifier is composed of MQW, polarization dependence appears remarkably in its gain characteristic. However, if the core layer is formed of a bulk layer and the core shape is isotropically manufactured, polarization dependency hardly occurs.
FIG. 12 shows the gain between the input and output fibers of this optical switch. In the figure, the solid line shows the characteristics of the polarization component horizontal to the substrate, and the broken line shows the characteristics of the polarization component vertical to the substrate. As shown in the figure, in this embodiment, since the bulk layer is used as the core layer, the polarization hardly depends on its characteristics.

Note that the same modifications as those of the first embodiment can be added to this embodiment. In addition, although the device for signal light of 1.3 μm band is used in the present embodiment, the invention is not limited to this. For example, the wavelength composition of the active core layer is 1.55 μm, and the wavelength composition of the passive core layer is 1.4 μm. , And can be applied to devices for 1.55 μm band signal light. Further, in the embodiment, the mask 12 is formed after the step of FIG.
Although the gap of 2 was widened, instead of this method, the mask may be removed once, and the dielectric film may be deposited and patterned to form a new mask.

[0045]

As described above, in the method of manufacturing an optical semiconductor integrated circuit according to the present invention, a plurality of regions having different mask widths are provided and the growth pressure is 500 Torr or more to perform crystal growth by the vapor phase selective growth method. Since it is a thing, MQ
When a W core layer is manufactured, a wavelength composition change of at least 300 nm or more can be obtained. Therefore, a low-loss passive waveguide and each core layer of, for example, a 1.3 μm band active optical element and a 1.55 μm band active optical element are used. It can be realized in the same crystal growth process.
Further, when a bulk core layer is manufactured by the above method, a wavelength composition change of at least 150 nm or more can be obtained. Therefore, for example, a core layer of a low loss passive waveguide having a composition of 1.15 μm and a core of a 1.3 μm band active optical element are used. Layers and 1 at the same time
It can be realized in one crystal growth step. Therefore, according to the present invention, the manufacturing method can be simplified, and the reproducibility and the yield can be improved. Further, since a plurality of core layers having different wavelength compositions can be formed continuously, it is possible to prevent coupling loss between optical elements from occurring, and to provide an optical semiconductor integrated circuit with small internal loss. It will be possible.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of an optical semiconductor integrated circuit formed according to a first embodiment of the present invention.

FIG. 2 is a line AA ′, a line BB ′, a line CC ′ of FIG.
Sectional drawing in the DD 'line.

3A to 3C are perspective views in order of steps for explaining the manufacturing method according to the first embodiment of the present invention.

4A to 4C are cross-sectional views in order of steps in a step that follows the step of FIG. 3 for explaining the manufacturing method according to the first embodiment of the present invention.

FIG. 5 is a graph showing the relationship between the mask width and the wavelength composition of the MQW core layer, for explaining the effect of the first embodiment of the present invention.

FIG. 6 is a graph showing the relationship between the growth pressure and the wavelength composition difference during vapor phase growth.

FIG. 7 is a graph showing the relationship between the wavelength composition of the MQW core layer and the waveguide loss measured with a signal light of 1.3 μm.

8A and 8B are a plan view and a partial perspective view showing a configuration of an optical semiconductor integrated circuit manufactured according to a second embodiment of the present invention.

9A and 9B are a sectional view and a plan view in order of steps for explaining a second embodiment of the present invention.

FIG. 10 is a graph showing the relationship between the mask width and the wavelength composition of the bulk core layer for explaining the effect of the second embodiment of the present invention.

FIG. 11 is a graph showing the relationship between the wavelength composition of the bulk core layer and the loss of signal light with a wavelength of 1.3 μm for explaining the effect of the second embodiment of the present invention.

FIG. 12 is a graph showing the relationship between the gate current and the gain between the input and output fibers for explaining the effect of the second embodiment of the present invention.

[Explanation of symbols]

1 WDM coupler 2 Y-branch 3 1.3 μm band transmission LD 4 1.3 μm band reception PD 5 1.55 μm band reception PD 11 n-InP substrate 12 n-InGaAsP layer 13 n-InP spacer layer 14 lower SCH layer 15 MQW layer 16 Upper SCH layer 17 InP clad layer 18 InP buried layer 20 Grating 21 SiO ₂ film 22 Mask for selective crystal growth 101 Gate part 102 Multiplexing / branching waveguide part 111 n-InP substrate 112 1.15 μm composition InGaAsP Passive core layer 113 1.3 μm composition InGaAsP active core layer 114 p-InP clad layer 115 p-InGaAs cap layer 116 Au / Ti metal layer 121 SiO ₂ film 122 mask for selective crystal growth 123 void Wm mask width Wg mask void

Claims (4)

[Claims] 1. A process of (1) depositing a dielectric film on a semiconductor substrate, and (2) selectively removing the dielectric film to form a pair of a predetermined width with a gap of a predetermined width. A step of forming a plurality of masks made of a striped dielectric film, and (3) a growth pressure of 500 Torr in the void portion of the mask.
a step of selectively growing the semiconductor core layer by a vapor phase growth method of r or more; (4) expanding the void portion of the mask or removing the mask and depositing a dielectric film again to form a striped dielectric film; A step of forming the buried layer surrounding the semiconductor core layer after processing or removing the mask, and a method for manufacturing an optical semiconductor integrated circuit. 2. The vapor phase epitaxy method in the step (3) is a metal organic vapor phase epitaxy method.
A method for manufacturing the optical semiconductor integrated circuit described. 3. The semiconductor core layer formed in the third step is InGaAs, InGaAsP, In
2. The optical semiconductor integrated device according to claim 1, wherein the bulk layer is made of GaAlAs or InGaAlAsP, or is a multi-quantum well layer having a well layer made of one of these materials. Circuit manufacturing method. 4. A pair of dielectric films having a width different from that of at least one end of the striped dielectric pair formed in the second step (2) is continuously formed thereon. The method for manufacturing an optical semiconductor integrated circuit according to claim 1.